JSFiddle - React, Tailwind, and code Playground

HTML

<header>
    <br />
    <br />
    <br />
    <br />
</header>

<img src="http://i.imgur.com/qKsVr.png" />

CSS

body {
    padding:20px;               
}

header {
    width: 240px;
    background-color: #BCED91;
}
header:after {
   content: " ";
   display:block;
   position: relative;
   width: 240px;
   bottom: -15px;
   height:15px;
   background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACgAAAAPCAYAAACWV43jAAAAw0lEQVRIx83RsQ3CMBCF4T83AZKLVOmyBa1HSIlXwKySGaDOBClZAToWQIpETQONyxAS+2J4pe9knd5X9EP7QicPYAsUwBnYaHwqSsd1QGmNv1rjL0AZ3pJTKDTorPGnsUE/tDvg+KsG70D96TiAMKvDbtYDO6Cyxt++LYadKpY8hthNtTaVGHLRJJ3R5mJy0SbVJp9D7FJaSyWXNUk1yGVt0lTyMWK3ZmtLySUnaQy55CZdSi7AHmis8U/+JOGWBji8AaYPVy6VELZvAAAAAElFTkSuQmCC) repeat-x;
}

img {
    margin-top:50px;
}